Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<iostream>
#include<queue>
using namespace std;

int h, w, white;
char c[60][60];
int maze[60][60];
int dx[4] = { 0,1,0,-1 }, dy[4] = { 1,0,-1,0 };
typedef pair<int, int> pint;

int main() {
	cin >> h >> w;
	for (int i = 1; i <= h; i++) {
		for (int j = 1; j <= w; j++) {
			cin >> c[i][j];
			if (c[i][j] == '.')white++;
		}
	}
	queue<pint>que;
	que.push(pint(1,1));
	c[1][1] = '#';
	int nx, ny, ans;
	while (!que.empty()) {
		pint a = que.front(); que.pop();
		for (int i = 0; i < 4; i++) {
			ny = a.first + dy[i], nx = a.second + dx[i];
			if (nx >= 1 && nx <= w&&ny >= 1 && ny <= h&&c[ny][nx] != '#'&&maze[ny][nx] == 0) {
				que.push(pint(ny, nx));
				maze[ny][nx] = maze[a.first][a.second] + 1;
			}
		}
	}
	if (maze[h][w] == 0)ans = -1;
	else ans = white - 1 - maze[h][w];
	cout << ans << endl;
	return 0;
}